Land-Use Intensity Reversed the Role of Cropland in Ecological Restoration Over the World's Most Severe Soil Erosion Region

Long-term extending cultivation activities resulted in the world's worst soil erosion on the Chinese Loess Plateau (LP). By converting cropland into vegetated land, the Grain for Green Project (GfGP)-the world's largest investment revegetation project-effectively alleviates the soil erosion on the LP. However, during the GfGP implementation, the positive effect of cropland to the revegetation and soil erosion control has been underestimated to date, hindering a comprehensive evaluation to the effect of cropland on ecological restoration. Here, we evaluated the effect of the GfGP on soil erosion control across the LP, analyzed the dominant driver of the LP vegetation greening, and further identified the contributions of croplands to this world's largest revegetation project. We found that the vegetation of the LP was significantly improved and its leaf area increased by 1.23 x 10(5) km(2) after the implementation of the GfGP, which contributed 42% to the decrease of the LP soil loss. Among them, our results show that cropland contributed 39.3% to the increased leaf areas of the LP, higher than grassland (36.3%) and forestland (14.3%). With the reduction of agricultural area, the contribution of cropland to the increased leaf areas in the LP was still the largest, which was mainly due to the increase in cropland utilization intensity. This study highlights the significance of the GfGP in soil erosion control and revises our understanding of the role of cropland in ecological restoration and society development.